Definitely run the heater and filter 24/7. Sounds like you will have to cycle the tank. When I did mine, the first month I was doing a 20% every other day and 7th day I did 50%. Once the tank cycled I do a 50% change once a week.

You'll have to cycle it first. Most people don't water change during the cycle, although you may need to if you're housing bettas during this period.

Generally speaking, if all parameters are ideal, no food is settling on the bottom and you've been spike-free for a while, I recommend 20% every 2 weeks. Of course, it'll take a while to reach that point. Water testing is your friend and is a fine indicator of when you need to do a water change. :)

Yea My 10g gets a 30% every 2 weeks normally. Recently I had been doing a few more since I had some melting plant drama :P But now that its been cleared up, my LFS who does my weekly tests wants me to teach all newbies how to get the tank that stable. They even told me in another month or 2 I will be down to one 50% a month. But then again my tank has been running since November last year. On my 5g I change 25% every week, with a gravel vac. But since my boys are not over fed, no left over foods, their water is just a clear and healthy as the 10g.